In recent years, a cutting tool having a longer tool life than in the case of a conventional cutting tool has been required, along with the improvement of highly efficient cutting. Thus, in terms of the performance required for tool materials, improvements of wear resistance and fracture resistance, which are directly related to the tool life, have been becoming increasingly important. In view of this, in order to improve such characteristics, a coated cutting tool is widely used which includes: a substrate comprised of a cemented carbide, cermet, cBN or the like; and a coating layer provided on a surface of the substrate, the coating layer consisting of one layer or two or more layers each comprised of a TiN layer, a TiAlN layer or the like.
Various techniques have been proposed in order to improve the characteristics of the above-described coating layer. For example, Patent Document 1 proposes a coated cutting tool in which a composite nitride of Ti and Al, which has a ratio of Ti/Al that falls within a range of 20/80 or more to 60/40 or less, is formed on a surface of a substrate.
Patent Document 2 proposes a coated cutting tool in which: compounds of two kinds, i.e., TixAl1-xN and TiyAl1-yN (0≤x<0.5, 0.5<y≤1) are laminated in an alternating manner; and the resulting laminate is aluminum rich in its entirety.